This invention is drawn to the field of underwater acoustics, and more particularly, to a low drag homing torpedo nose assembly having side mounted planar arrays, which, with suitable associated electronics, are capable of forming a plurality of preformed beams displaying an azimuth which selectively extends from vehicle fore to vehicle aft.
Conventional homing torpedos use an acoustic sensor of the so-called forward looking variety which typically comprises a planar array of transducer elements mounted in a blunt shaped nose section of the vehicle in such a manner that the beams formed by the array selectively display an azimuth centered to vehicle fore. U.S. Pat. No. 4,192,246, issued Mar. 11, 1980 to Hodges et al, incorporated herein by reference, is exemplary of the forward looking acoustic homing torpedo.
In order to search those regions of an aqueous medium which lie outside the azimuth of the forward looking array, the torpedo executes a preprogrammed snake-like path which points the nose assembly to port and to starboard repetitively. The torpedo switches to an attack mode after target detection and adopts a course calculated to intercept the target. Whenever the target vehicle is moving, the intercept course closes the torpedo on a nonperpendicular angle of attack. In such a situation, it often happens that the forward looking sensor loses track of the target vehicle and the torpedo must again switch back to the search mode.
Thus, the extensive vehicle maneuvering, which is often required by this search and close procedure, when combined with significant hydrodynamic drag resulting from, among other factors, the blunt shaped nose assembly, effectively limits maximum range for a given quantity of fuel. Conversely, for a given range, it places a minimum limit on the quantity of the fuel required, which is often fifty (50) to sixty (60) percent of vehicle volume, thereby detracting from the payload volume.